Matthew Island and Hunter Island are two uninhabited volcanic islands in the South Pacific, east of New Caledonia and south-east of Vanuatu. The pair, which lie apart, are claimed by Vanuatu as part of Tafea Province, and considered by the people of Aneityum part of their custom ownership, but also claimed by France as part of New Caledonia.
Small, arid, without fresh water and not easily accessible, the islands had no interest for Britain or France during their colonisation of the Pacific in the course of the 18th and 19th centuries. France officially annexed both islands in 1929. In 1965, the United Kingdom also claimed the two islands, as part of the New Hebrides. France conducted a symbolic occupation in 1975. In 1980, on its independence, Vanuatu claimed sovereignty, but made no occupation of the islands. In 1979, Météo-France set up an automatic weather station on one of the islands, and the French Navy regularly visits both of them.
Hunter Island
Hunter Island () is also known, as "Fern or Fearn Island", or "Leka" in the local language of Futuna island in southern Vanuatu. The first recorded European sighting of the island was by Captain Thomas Fearn from his trading ship Hunter in 1798. It lies about east of Matthew Island. About in area, the island has a domed shape, and some sources suggest a height of its highest peak, Mont Favard, of , but others are higher. It was first surveyed by the British between 1853 and 1856 at high which is still given in a recent English source. There has been volcanic activity since 1856 and before 1982 French aviation photographic studies were interpreted to give an approximate height of . Other French sources are slightly higher.<!--see talk for more details----> It is composed of andesite – dacitic lavas and numerous explosion craters dot the stratovolcano. A cone makes up the south part of the island, with its central crater filled by a lava dome. A -deep crater is located on the north-west side of the island.<!--see talk for more details---->
Volcanic activity
Fumarolic and solfataric activity continues in the north of the island, as well as on the northeast and southeast coasts.
Matthew Island
thumb|Matthew Island aerial view
Matthew Island () is also known as Umaenupne island in the indigenous language of Aneityum island in southern Vanuatu, the closest inhabited island. It is in area, . The volcanic island is composed of two andesitic-to-dactic volcanic cones, East Matthew and West Matthew, separated by a rocky 200-metre-wide isthmus. The island was discovered by Captain Thomas Gilbert, of , on 27 May 1788, who named it after the owner of his ship. At the time of the discovery, only East Matthew existed and it was described as having only one peak prior to the Second World War.
East Matthew is the older part of the island, formed from basalt with a half-destroyed, high composite volcanic cone that is thought to be composed of three lava flows. There is still some volcanic activity on the island with sulphuric fumaroles rising from craters in the south-east. West Matthew formed in the late 1940s and may have had eruptions as recent as 1976. It is a roughly circular, high cone with a serrated peak and is composed almost entirely of lava flows and slag.
Eruptions
All known historical eruptions have come from West Matthew. After a highly seismically active period in the 1940s, construction of West Matthew began as submarine eruptions built up a new island. The new cone then emitted lava flows. The eruption was a VEI 2. Another VEI 2 eruption from West Matthew took place in October 1954, while a very small (VEI 0) fissure eruption occurred in approximately 1956. This marks the latest confirmed activity on Matthew Island, although tremors took place near the island in 2008, 2009 and 2011. Uncertainty surrounds a report of an eruption in 1828, as well as reports of eruptions in 1966 and 1976.
Important Bird Area
The island has been recognised as an Important Bird Area (IBA) by BirdLife International because it supports breeding populations of brown boobies and blue noddies.
Registry
In March 2025, it was reported that the Island was being used as a fraudulent ship register under the flag of the fictional Maritime Administration of Matthew Island (MAMI).
Seismicity
The islands are prone to earthquakes, as they are situated near the southern arc of the South New Hebrides Trench, where the minor New Hebrides plate is subducted by the Australian plate. In February 2021, a 7.7 quake was centered in the vicinity of Matthew and Hunter.
Tectonics
Both Matthew Island and Hunter Island are within the Hunter Ridge part of the New Hebrides plate, which was initially formed from about 7 to 3 million years ago, when the opening of the North Fiji Basin in a north–south direction allowed northward subduction of the South Fiji Basin part of the then Indo-Australian plate under the North Fiji Basin. From about 3 million years ago the current triple junction between the New Hebrides plate, Australian plate and the Conway Reef plate became established and the southernmost propagating tip of the Central Spreading Ridge backarc-spreading centre in the North Fiji Basin over the last 2 million years has rifted westward splitting the Hunter Ridge into two halves. New young subduction of the South Fiji Basin has created what has been called the Matthew and Hunter subduction zone.